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  • A Voting Scheme for BLOB Replication

    A Writing Project

    Presented to

    The Faculty of the Department of Computer Science

    San Jose State University

    In Partial Fulfillment of the Requirement for the

    Degree

    Master of Science

    By

    Preethi Vishwanath

    May 2007

    Preethi Vishwanath Page 1 5/15/2007

  • © 2007

    Preethi Vishwanath

    ALL RIGHTS RESERVED

    Preethi Vishwanath Page 2 5/15/2007

  • APPROVED FOR THE DEPARTMENT OF COMPUTER SCIENCE

    Dr. Chris Pollett

    Dr. Robert Chun

    Mr. Tuong Truong

    Preethi Vishwanath Page 3 5/15/2007

  • Abstract

    The introduction of handheld devices has thrown up interesting research issues in the areas of BLOB replication in highly mobile ad-hoc wireless networks. One of such handheld device, Microsoft’s Zune MP3 music player not only acts as a warehouse (30G) of audio and video data, but also exploits its in-build Wi-Fi capability to allow for exchange of these streams between any two players in close vicinity to each other. Our work proposes the use of a distributed, topologically aware Byzantine algorithm for creating BLOB replicas in the ad-hoc network. We also provide simulation results of our algorithms under different topologies and replicas created from our test bench. We also compare our work against other [8] [18] algorithms for BLOB replication in ad-hoc wireless networks.

    Keywords: Ad-hoc networks, replication, Binary Large Objects, Byzantine

    Preethi Vishwanath Page 4 5/15/2007

  • Table of Contents

    1 Introduction ....................................................................................................................... 7 2 Background and Theory .................................................................................................... 9

    2.1 Mobile ad-hoc networks ............................................................................................. 9 2.2 XML .......................................................................................................................... 10 2.3 Byzantine algorithm .................................................................................................. 10 2.4 Java RMI ................................................................................................................... 11

    3 Replica Allocation Methods ........................................................................................... 12 3.1 Byzantine replication ............................................................................................... 12 3.2 Constant Broadcast Replication ................................................................................ 14 3.3 Static Access Frequency Replication ........................................................................ 15 3.4 Dynamic Access Frequency Neighborhood Replication .......................................... 16

    4 Software Design ............................................................................................................. 18 4.1 Software Architecture ............................................................................................... 18

    i XML Processing ...................................................................................................................................... 19 ii Network Model ...................................................................................................... 22 iii Byzantine Replication Algorithm ......................................................................... 23

    4.2 Design of our Setup .................................................................................................. 24 i System Manager ..................................................................................................... 24 ii Mesh Manager ....................................................................................................... 25 iii Node Entity ........................................................................................................... 25

    5 Experimental Setup ......................................................................................................... 27 5.1 Introduction ............................................................................................................... 27 5.2 A Ring Topology ...................................................................................................... 27

    6 Results ............................................................................................................................. 30 6.1 XML Parser ............................................................................................................... 30 6.2 Ring Model ............................................................................................................... 31 6.3 Tree Model ................................................................................................................ 31 6.4 Analysis - Ring Model .............................................................................................. 33 6.5 Analysis - Tree Model .............................................................................................. 34

    7 Comparison ..................................................................................................................... 37 7.1 Continuous Broadcast (CB) Replication ................................................................... 37

    i Setup ....................................................................................................................... 37 ii Analysis – Results .................................................................................................. 37

    7.2 Static Access Frequency (SAF) Model ..................................................................... 39 i Setup ............................................................................................................

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